1. Field of the Invention
The present invention relates to an air conditioning apparatus wherein a direction of an air flow is controlled by a film member.
2. Description of the Related Art
An air conditioning apparatus wherein a film member is used for controlling a direction of a flow of air is disclosed in the Journal of Nippon Denso Technical Disclosures, published on Feb. 15, 1990.
In this prior art, a film member is used as a damper (film damper) to select an air outlet mode for introducing an air flow into a desired location of the cabin. The film damper has two ends, which are connected to separate shafts connected with each other by a belt moved by an electric motor. When the shafts are rotated, one of the ends of the damper is wound onto one of the shafts, and the other end of the damper is unwound from the other shaft, whereby an opening formed in the damper is aligned with a desired outlet to thereby obtain a desired air flow mode.
In the prior art, the amount of film member wound onto one of the shafts, and the amount of the film damper wound onto the other shaft are different, and depend on the outlet mode selected. This means that the entire outer diameter of the shaft on which a larger amount of the film damper is wound is larger than that of the shaft on which a smaller amount of the film damper is wound.
In the prior art construction wherein two shafts are driven by the same belt, these shafts are rotated at the same rotational speed, but the difference in the total diameters, including the thickness of the film wound thereon of the two shafts, may cause the speed of the film wound up or fed by one of the shafts to differ from the speed of the film fed by or wound up on the other shaft, and thus the film moving between the shafts is overstretched or becomes too slack. The overstretching or slackening of the film member makes an opening in the film member out of register, i.e. to be misaligned, and thus problems arise in that a noise is generated or a leakage of air occurs.